Cisco Nexus 7000 Series Configuration Manual page 314

General SPAN Guidelines and Limitations
• If a module is not in the VDC in which the inband interface is sourced, packets destined to the supervisor
cannot be captured.
• For Cisco NX-OS releases prior to 6.1, you can monitor the inband interface only from the default VDC.
Inband traffic from all VDCs is monitored. Beginning with Cisco NX-OS Release 6.1, the monitoring
of the inband interface is no longer restricted to the default VDC:
• Inband SPAN is treated as a shared resource. If a particular VDC does not have the resource allocated
to it, inband port sourcing is rejected. Similarly, if a VDC that has the inband supervisor resource allocated
to it removes the inband port from the source list of all monitor sessions, the inband resource is released
from that VDC.
• For the supervisor inband interface, SPAN is supported only in the VDC in which the inband interface
is sourced. If a module is part of a VDC in which the inband interface is not sourced, at least one interface
of the module must be in the VDC in which the inband interface is sourced in order to capture supervisor
inband packets from this module.
• A single SPAN session can include mixed sources in any combination of the following:
• When a SPAN session contains both source interfaces and source VLAN clauses, there is a possibility
that other VLANs also will be spanned.
• Destination ports do not participate in any spanning tree instance. SPAN output includes bridge protocol
data unit (BPDU) Spanning-Tree Protocol hello packets.
• When a SPAN session contains source ports or VLAN sources that are monitored in the transmit or
transmit and receive direction, packets that these ports receive might be replicated to the SPAN destination
port even though the packets are not actually transmitted on the source ports. Some examples of this
behavior on source ports are as follows:
• You can enable SPAN for a source port before it becomes operationally active. Thus for Layer 2 ports,
traffic flooded to the VLANs that contain these ports are captured even when the link is not connected
for the ports.
• For VLAN SPAN sessions with both ingress and egress configured, two packets (one from ingress and
one from egress) are forwarded from the destination port if the packets get switched on the same VLAN.
• Beginning with Cisco NX-OS Release 6.2(2), the spanning of inband interfaces is as follows:
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◦ Only users with the network admin privilege can add the inband interface as a SPAN source.
◦ The inband interface can be added as a source from any VDC except the admin VDC, but at any
time, only one VDC can have the inband interface as a source.
◦ Ethernet ports, but not subinterfaces
◦ VLANs, that can be assigned to port channel subinterfaces
◦ The inband interface to the control plane CPU
◦ Traffic that results from flooding
◦ Broadcast and multicast traffic
◦ For Supervisor 1 systems, the two bidirectional traditional sessions can support an inband SPAN
source.
Configuring SPAN